1. Field of the Invention
The present invention is generally in the field of electrical circuits and systems. More specifically, the present invention is in the field of circuits and systems for use in driving inductive loads.
2. Background Art
Inductive loads, such as electric motors, pumps, fans, and the like, are typically driven at high frequencies to avoid the drawbacks associated with use of conventional low frequency drivers. For example, driving an inductive load, such as a brushed direct current (DC) motor, at low frequency can give rise to undesirable mechanical vibrations and acoustic noise. Despite their success in driving inductive loads without producing substantial vibrations or acoustic noise, conventional approaches to using high frequency drivers are associated with significant disadvantages as well. For instance, use of a high frequency driver to drive a DC brushed motor can be inefficient due to substantial power losses, such as switching losses in the power semiconductor devices implemented to provide the motor drive current, for example.
Historically, sacrificing operating efficiency for smooth and largely noise free motor performance has been considered an acceptable tradeoff. However, as the goal of reducing power consumption, especially in the form of unnecessary power losses, becomes an increasingly important and even mandated design objective, the reductions in switching losses achievable through use of low frequency drivers has become more compelling.
One known approach to using a low frequency driver to drive a DC brushed motor uses metal-oxide-semiconductor field-effect transistor (MOSFET) power switches to drive the motor, and operates those MOSFET power switches in linear mode. By successfully reducing the abruptness of the switching transition through linear operation of the MOSFET power switches, this approach has achieved considerable success in driving a DC brushed motor, or other inductive load, at low frequency, while also reducing mechanical vibrations and acoustic noise. However, operating MOSFET power devices in linear mode is itself quite inefficient, and the described approach yields little or none of the power saving advantages typically associated with use of a low frequency driver.
Thus, there is a need to overcome the drawbacks and deficiencies in the art by providing a drive control circuit configured to enable low power loss operation of a coupled switching circuit while concurrently reducing or eliminating mechanical vibrations and acoustic noise in an inductive load driven by the switching circuit.